Propylene copolymer for thin-wall packaging

ABSTRACT

Propylene copolymer having a comonomer content in the range of 2.0 to 11.0 mol.-% and a melt flow rate MFR 2  (230° C.) in the range of 25.0 to 100 g/10 min, wherein said propylene copolymer is featured by good toughness.

The present invention relates to a new propylene copolymer, to itsmanufacture as well as to thin-wall packaging comprising said newpropylene copolymer.

In the field of thin-wall packaging it is of great importance to have awell flowing material with good mechanical properties, i.e. a hightensile modulus and good impact strength. The good flowability is neededfor achieving a good processability in various manufacturing methods ofarticles, e.g. injection molding processes, thereby allowing the highproduction speed required in this mass production market. The mechanicalproperties are also critical in view of the thin-walled articles.Particularly, in the field of containers there is a need to hold thecontent such as food contained therein as well as having sufficientstiffness to be stacked. Finally, the materials should also withstandmechanical impact damage, which is frequently incurred by e.g. droppingthe articles.

Still further, also the haze should be acceptable. Particularly, a goodbalance between stiffness and haze is desirable.

However, at least some of these objects may only be achieved at theexpense of others of these objects. For instance with increase of meltflow rate the stiffness can be improved, however the impact propertiessignificantly drop. Thus impact behavior and melt flow of a polymerbehave in a conflicting manner.

Further a high degree of crystallinity of polypropylene renders thematerial rather stiff, however also increases the haze. Thecrystallinity is influenced by the amount of comonomer contained in thepolymer and by the insertion of the comonomer in the polymer chain.

It is therefore an object of the present invention to provide apolypropylene which enables a skilled person to produce thin-wallpackaging in an economically way. Accordingly it is in particular anobject of the present invention to provide a polypropylene with highflowability and at the same time keeping impact properties and opticalproperties on a high level.

The finding of the present invention is to provide a propylene copolymerwith rather high melt flow rate and being monophasic, while having amoderate to low randomness.

Accordingly the present invention is directed to a propylene copolymer(R-PP) having

-   (a) a comonomer content in the range of 2.0 to 11.0 mol.-%;-   (b) a melt flow rate MFR2 (230° C.) measured according to ISO 1133    in the range of 25.0 to 100 g/10 min; and-   (c) a relative content of isolated to block ethylene sequences    (I(E)) in the range of 45.0 to 70.0%, wherein the I(E) content is    defined by equation (I)

$\begin{matrix}{{I(E)} = {\frac{f\; {PEP}}{\left( {{f\; {EEE}} + {f\; {PEE}} + {f\; {PEP}}} \right)} \times 100}} & (I)\end{matrix}$

-   -   wherein    -   I(E) is the relative content of isolated to block ethylene        sequences [in %];    -   fPEP is the mol fraction of propylene/ethylene/propylene        sequences (PEP) in the sample;    -   fPEE is the mol fraction of propylene/ethylene/ethylene        sequences (PEE) and of ethylene/ethylene/propylene sequences        (EEP) in the sample;    -   fEEE is the mol fraction of ethylene/ethylene/ethylene sequences        (EEE) in the sample    -   wherein all sequence concentrations being based on a statistical        triad analysis of ¹³C-NMR data.

Preferably the propylene copolymer (R-PP) is monophasic. Alternativelyor additionally the propylene copolymer (R-PP) has preferably no glasstransition temperature below −20° C.

Surprisingly the propylene copolymer (R-PP) according to the inventionhas high impact and good optical properties even though the melt flowrate MFR₂ (230° C.) is relatively high.

Therefore in one specific embodiment the present invention is directedto an injection molded article, like a thin wall packaging element,comprising the propylene copolymer (R-PP) of the present invention. Morepreferably the present invention is directed to a thin wall packagingelement selected from the group consisting of cups, boxes, trays, pails,buckets, bowls, lids, flaps, caps, CD covers, and DVD covers, whereinsaid thin wall packaging element comprises the propylene copolymer(R-PP) of the present invention.

In the following the propylene copolymer (R-PP) is defined in moredetail.

As mentioned above the propylene copolymer (R-PP) according to thisinvention is preferably monophasic. Accordingly it is preferred that thepropylene copolymer (R-PP) does not contain elastomeric (co)polymersforming inclusions as a second phase for improving mechanicalproperties. A polymer containing elastomeric (co)polymers as insertionsof a second phase would by contrast be called heterophasic and ispreferably not part of the present invention. The presence of secondphases or the so called inclusions are for instance visible by highresolution microscopy, like electron microscopy or atomic forcemicroscopy, or by dynamic mechanical thermal analysis (DMTA).Specifically in DMTA the presence of a multiphase structure can beidentified by the presence of at least two distinct glass transitiontemperatures.

Accordingly it is preferred that the propylene copolymer (R-PP)according to this invention has no glass transition temperature below−30, preferably below −25° C., more preferably below −20° C.

On the other hand, in one preferred embodiment the propylene copolymer(R-PP) according to this invention has a glass transition temperature inthe range of −12 to +2° C., more preferably in the range of −10 to +2°C.

The propylene copolymer (R-PP) according to this invention has a meltflow rate MFR₂ (230° C.) measured according to ISO 1133 in the range of25.0 to 100 g/10 min, more preferably in the range of 28.0 to 90 g/10min, still more preferably in the range of 30.0 to 80 g/10 min.

The propylene copolymer (R-PP) comprises apart from propylene alsocomonomers. Preferably the propylene copolymer (R-PP) comprises apartfrom propylene ethylene and/or C₄ to C₁₂ α-olefins. Accordingly the term“propylene copolymer” according to this invention is preferablyunderstood as a polypropylene comprising, preferably consisting of,units derivable from

(a) propyleneand(b) ethylene and/or C₄ to C₁₂ α-olefins.

Thus the propylene copolymer (R-PP) according to this inventionpreferably comprises monomers copolymerizable with propylene, forexample comonomers such as ethylene and/or C₄ to C₁₂ α-olefins, inparticular ethylene and/or C₄ to C₈ α-olefins, e.g. 1-butene and/or1-hexene. Preferably the propylene copolymer (R-PP) according to thisinvention comprises, especially consists of, monomers copolymerizablewith propylene from the group consisting of ethylene, 1-butene and1-hexene. More specifically the propylene copolymer (R-PP) of thisinvention comprises—apart from propylene—units derivable from ethyleneand/or 1-butene. In a preferred embodiment the propylene copolymer(R-PP) according to this invention comprises units derivable fromethylene and propylene only.

Additionally it is appreciated that the propylene copolymer (R-PP)preferably has a comonomer content in a very specific range whichcontributes to the impact strength and the good optical properties. Thusit is required that the comonomer content of the propylene copolymer(R-PP) is in the range of 2.0 to below 11.0 mol-%, preferably in therange of 2.5 to below 10.0 mol.-%, more preferably in the range of 3.0to below 9.5 mol.-%, still more preferably in the range of 3.5 to 9.0mol.-%, yet more preferably in the range of 4.0 to 8.5 mol.-%.

Further the propylene copolymer is featured by its relative content ofisolated to block ethylene sequences (I(E). The I(E) content [%] isdefined by equation (I)

$\begin{matrix}{{I(E)} = {\frac{f\; {PEP}}{\left( {{f\; {EEE}} + {f\; {PEE}} + {f\; {PEP}}} \right)} \times 100}} & (I)\end{matrix}$

whereinI(E) is the relative content of isolated to block ethylene sequences [in%];fPEP is the mol fraction of propylene/ethylene/propylene sequences (PEP)in the sample;fPEE is the mol fraction of propylene/ethylene/ethylene sequences (PEE)and of ethylene/ethylene/propylene sequences (EEP) in the sample;fEEE is the mol fraction of ethylene/ethylene/ethylene sequences (EEE)in the sample wherein all sequence concentrations being based on astatistical triad analysis of ¹³C-NMR data.

Accordingly it is preferred that the propylene copolymer (R-PP) has anormalized PEP value (nPEP) in the range 45.0 to 70.0%, more preferablyin the range of 50.0 to 70.0%, still more preferably in the range of55.0 to 70.0%, yet more preferably in the range of 58.0 to 69.0%.

Further the propylene copolymer (R-PP) has a main melting temperature,i.e. a melting temperature representing more than 50% of the meltingenthalpy, of at least 130° C., more preferably in the range of 133 to155° C., still more preferably in the range of 134 to 152° C.

Further it is preferred that the propylene copolymer (R-PP) has acrystallization temperature of at least 110° C., more preferably in therange of 110 to 128° C., still more preferably in the range of 112 to126° C., like in the range of 114 to 124° C.

Preferably, the propylene copolymer (R-PP) has a xylene cold solublefraction (XCS) in the range of 4.0 to 25.0 wt.-%, preferably in therange of 4.5 to 20.0 wt.-%, more preferably in the range of 5.0 to 15.0wt-%.

Further it is preferred that the propylene copolymer (R-PP) has a hexanesoluble content of below 6.0 wt.-%, more preferably in the range ofabove 1.0 to below 6.0 wt.-%, still more preferably in the range of 2.0to 5.0 wt.-%.

Preferably the propylene copolymer (R-PP) has a molecular weightdistribution (Mw/Mn) of at least 3.0, more preferably in the range of3.0 to 6.0, still more preferably in the range of 3.5 to 5.5, like inthe range of 3.7 to 5.3.

Additionally or alternatively to the molecular weight distribution(Mw/Mn) as defined in the previous paragraph the propylene copolymer(R-PP) has preferably weight average molecular weight Mw in the range of90 to 500 kg/mol, more preferably in the range of 90 to 250 kg/mol, likein the range of 100 to 220 kg/mol.

Preferably the propylene copolymer according to this invention has beenproduced in the presence of a Ziegler-Natta catalyst. The catalystinfluences in particular the microstructure of the polymer. Inparticular, polypropylenes prepared by using a metallocene catalystprovide a different microstructure compared to polypropylenes preparedby using Ziegler-Natta (ZN) catalysts. The most significant differenceis the presence of regio-defects in metallocene-made polypropyleneswhich is not the case for polypropylenes made by Ziegler-Natta (ZN). Theregio-defects can be of three different types, namely 2,1-erythro(2,1e), 2,1-threo (2,1t) and 3,1 defects. A detailed description of thestructure and mechanism of formation of regio-defects in polypropylenecan be found in Chemical Reviews 2000, 100(4), pages 1316-1327.

The term “2,1 regio defects” as used in the present invention definesthe sum of 2,1 erythro regio-defects and 2,1 threo regio-defects.

Accordingly it is preferred that the propylene copolymer (R-PP)according to this invention has 2,1 regio-defects, like 2,1 erythroregio-defects, of at most 0.4%, more preferably of at most 0.3%, stillmore preferably of at most 0.2%, determined by ¹³C-NMR spectroscopy. Inone specific embodiment no 2,1 regio-defects, like 2,1 erythroregio-defects, are detectable for the propylene copolymer (R-PP).

The propylene copolymer (R-PP) preferably comprises at least two polymerfractions, like two or three polymer fraction, all of them beingpropylene copolymers. Preferably the random propylene copolymer (R-PP)comprises at least two different propylene copolymer fractions, like twodifferent propylene copolymer fractions, wherein further the twopropylene copolymer fractions preferably differ in the comonomercontent.

Preferably one fraction of the two polymer copolymer fractions of thepropylene copolymer (R-PP) is the commoner lean fraction and the otherfraction is the comonomer rich fraction, wherein more preferably thelean fraction and the rich fraction fulfill together in-equation (II),more preferably in-equation (IIa), even more preferably in-equation(IIb), still more preferably in-equation (IIIc),

$\begin{matrix}{{\frac{{Co}({rich})}{{Co}({lean})} \geq 1.0},} & ({II}) \\{{1.0 \leq \frac{{Co}({rich})}{{Co}({lean})} \leq 4.0},} & ({IIa}) \\{1.2 \leq \frac{{Co}({rich})}{{Co}({lean})} \leq 3.0} & ({IIb}) \\{1.2 \leq \frac{{Co}({rich})}{{Co}({lean})} \leq 2.5} & ({IIc})\end{matrix}$

wherein

-   Co (lean) is the comonomer content [mol.-%] of the propylene    copolymer fraction with the lower comonomer content,-   Co (rich) is the comonomer content [mol.-%] of the propylene    copolymer fraction with the higher comonomer content.

In addition or alternatively to inequation (III) one fraction of the twopolymer copolymer fractions of the propylene copolymer (R-PP) is the lowmelt flow rate MFR₂ (230° C.) fraction and the other fraction is thehigh melt flow rate MFR₂ (230° C.) fraction, wherein more preferably thelow flow fraction and the high flow fraction fulfill together inequation(III), more preferably inequation (IIIa), still more preferablyinequation (IIIb),

$\begin{matrix}{\frac{{MFR}({high})}{{MFR}({low})} \geq 1.0} & ({III}) \\{1.0 \leq \frac{{MFR}({high})}{{MFR}({low})} \leq 3.0} & ({IIIa}) \\{1.0 \leq \frac{{MFR}({high})}{{MFR}({low})} \leq 2.0} & ({IIIb})\end{matrix}$

wherein

-   MFR (high) is the melt flow rate MFR₂ (230° C.) [g/10 min] of the    propylene copolymer fraction with the higher melt flow rate MFR₂    (230° C.),-   MFR (low) is the melt flow rate MFR₂ (230° C.) [g/10 min] of the    propylene copolymer fraction with the lower melt flow rate MFR₂    (230° C.).

Even more preferred the propylene copolymer (R-PP) comprises, preferablyconsists of, a first propylene copolymer fraction (R-PP1) and a secondpropylene copolymer fraction (R-PP2), wherein further the firstpropylene copolymer fraction (R-PP1) and the second propylene copolymerfraction (R-PP2) differ in the comonomer content and/or in the melt flowrate MFR₂ (230° C.). In one embodiment they differ in the comonomercontent and in the melt flow rate MFR₂ (230° C.).

Thus in one embodiment the first random propylene copolymer fraction(R-PP1) has a higher comonomer content and melt flow rate MFR₂ (230° C.)than the second random propylene copolymer fraction (R-PP2). [1^(st)option]

In another embodiment the first random propylene copolymer fraction(R-PP1) has a higher comonomer content but a lower melt flow rate MFR₂(230° C.) than the second random propylene copolymer fraction (R-PP2).[2^(nd) option]

In still another embodiment the first random propylene copolymerfraction (R-PP1) has a higher comonomer content than the second randompropylene copolymer fraction (R-PP2) and the melt flow rate MFR₂ (230°C.) of the first random propylene copolymer fraction (R-PP1) and thesecond random propylene copolymer fraction (R-PP2) are essentially thesame, e.g. differ by no more than 8 g/10 min, more preferably by no morethan 6 g/10 min, still more preferably by no more than 5 g/10 min.[3^(rd) option]

In still another embodiment the second random propylene copolymerfraction (R-PP2) has a higher comonomer content but a lower melt flowrate MFR₂ (230° C.) than the first random propylene copolymer fraction(R-PP1). [4^(th) option]

In further embodiment the second random propylene copolymer fraction(R-PP2) has a higher comonomer content and melt flow rate MFR₂ (230° C.)than the first random propylene copolymer fraction (R-PP1). Thisembodiment is especially preferred. [5^(th) option]

The 1^(st), 2^(nd) and 3^(rd) options are especially preferred.

Accordingly it is preferred that the first random propylene copolymerfraction (R-PP1) and the second random propylene copolymer fraction(R-PP2) fulfill together the in-equation (IV), more preferablyin-equation (IVa), even more preferably in-equation (IVb), still morepreferably in-equation (IVc),

$\begin{matrix}{{\frac{{Co}\left( {R - {{PP}\; 2}} \right)}{{Co}\left( {R - {{PP}\; 1}} \right)} \geq 1.0},} & ({IV}) \\{{1.0 \leq \frac{{Co}\left( {R - {{PP}\; 2}} \right)}{{Co}\left( {R - {{PP}\; 1}} \right)} \leq 4.0},} & ({IVa}) \\{{1.2 \leq \frac{{Co}\left( {R - {{PP}\; 2}} \right)}{{Co}\left( {R - {{PP}\; 1}} \right)} \leq 3.0},} & ({IVb}) \\{1.2 \leq \frac{{Co}\left( {R - {{PP}\; 2}} \right)}{{Co}\left( {R - {{PP}\; 1}} \right)} \leq 2.5} & ({IVc})\end{matrix}$

wherein

-   Co(R-PP1) is the comonomer content [mol.-%] of the first propylene    copolymer fraction (R-PP1),-   Co(R-PP2) is the comonomer content [mol.-%] of the second propylene    copolymer fraction (R-PP2).

It is especially preferred that the propylene copolymer (R-PP) hashigher comonomer content than the first random propylene copolymerfraction (R-PP1). Accordingly the random propylene copolymer (R-PP)comprises, preferably consists of, the first random propylene copolymerfraction (R-PP1) and the second random propylene copolymer fraction(R-PP2), wherein further the random propylene copolymer (R-PP) fulfills

(a) the in-equation (V), more preferably in-equation (Va), even morepreferably in-equation (Vb), still more preferably in-equation (Vc),

$\begin{matrix}{{\frac{{Co}\left( {R - {PP}} \right)}{{Co}\left( {R - {{PP}1}} \right)} \geq 1.0},} & (V) \\{{1.0 \leq \frac{{Co}\left( {R - {PP}} \right)}{{Co}\left( {R - {{PP}1}} \right)} \leq 3.0},} & ({Va}) \\{{1.0 \leq \frac{{Co}\left( {R - {PP}} \right)}{{Co}\left( {R - {{PP}1}} \right)} \leq 2.5},} & ({Vb}) \\{1.1 \leq \frac{{Co}\left( {R - {PP}} \right)}{{Co}\left( {R - {{PP}\; 1}} \right)} \leq 2.2} & ({Vc})\end{matrix}$

wherein

-   Co(R-PP1) is the comonomer content [mol.-%] of the first random    propylene copolymer fraction (R-PP1),-   Co(R-PP) is the comonomer content [mol.-%] of the propylene    copolymer (R-PP).

It is further preferred that the melt flow rate MFR₂ (230° C.) of thefirst random propylene copolymer fraction (R-PP1) to the melt flow rateMFR₂ (230° C.) of the propylene copolymer (R-PP) by no more than 8 g/10min, more preferably by no more than 6 g/10 min, still more preferablyby no more than 4 g/10 min.

Thus it is preferred that the first random propylene copolymer fraction(R-PP1) has a comonomer content of equal or below 8.0 mol-%, morepreferably of equal or below 7.0 mol-%, still more preferably of equalor below 6.0 mol-%, yet more preferably in the range 1.0 to 7.0 mol-%,still yet more preferably in the range 1.0 to 6.0 mol-%, like in therange 2.0 to 5.5 mol-%.

Preferably the first random propylene copolymer fraction (R-PP1)preferably has a melt flow rate MFR₂ (230° C.) in the range of in therange of 20.0 to 120 g/10 min, more preferably in the range 25.0 to 100g/10 min, still more preferably in the range of 25.0 to 80 g/10 min.

On the other hand the second random propylene copolymer fraction (R-PP2)preferably has a comonomer content of at least 4.0 mol-%, morepreferably of at least 5.0 wt.-%, still more preferably of more than 6.0mol-%, yet more preferably in the range of 5.0 to 14.0 mol-%, still morepreferably in the range of more than 6.0 to 14.0 mol-%, still yet morepreferably in the range 6.1 to 12.0 mol-%.

Preferably the second random propylene copolymer fraction (R-PP2)preferably has a melt flow rate MFR₂ (230° C.) in the range of 20.0 to120 g/10 min, more preferably in the range of 25.0 to 100 g/10 min,still more preferably in the range of 25.0 to 80 g/10 min.

The comonomers of the first propylene copolymer fraction (R-PP1) andrandom propylene copolymer fraction (R-PP2), respectively,copolymerizable with propylene are ethylene and/or C₄ to C₁₂ α-olefins,in particular ethylene and/or C₄ to C₈ α-olefins, e.g. 1-butene and/or1-hexene. Preferably the first propylene copolymer fraction (R-PP1) andsecond propylene copolymer fraction (R-PP2), respectively, comprise,especially consist of, monomers copolymerizable with propylene from thegroup consisting of ethylene, 1-butene and 1-hexene. More specificallythe first propylene copolymer fraction (R-PP1) and second propylenecopolymer fraction (R-PP2), respectively, comprise—apart frompropylene—units derivable from ethylene and/or 1-butene. In a preferredembodiment the first propylene copolymer fraction (R-PP1) and the secondpropylene copolymer fraction (R-PP2) comprise the same comonomers, i.e.ethylene only.

Preferably the weight ratio between the first propylene copolymerfraction (R-PP1) and the second propylene copolymer fraction (R-PP2) is20/80 to 80/20, more preferably 30/70 to 70/30, like 35/65 to 65/35.

The propylene copolymer (R-PP) as defined in the instant invention maycontain up to 5.0 wt.-% additives, like α-nucleating agents andantioxidants, as well as slip agents and antiblocking agents. Preferablythe additive content (without α-nucleating agents) is below 3.0 wt.-%,like below 1.0 wt.-%.

Preferably the propylene copolymer (R-PP) comprises a α-nucleatingagent. Even more preferred the present invention is free of β-nucleatingagents. The α-nucleating agent is preferably selected from the groupconsisting of

-   (i) salts of monocarboxylic acids and polycarboxylic acids, e.g.    sodium benzoate or aluminum tert-butylbenzoate, and-   (ii) dibenzylidenesorbitol (e.g. 1,3:2,4 dibenzylidenesorbitol) and    C₁-C₈-alkyl-substituted dibenzylidenesorbitol derivatives, such as    methyldibenzylidenesorbitol, ethyldibenzylidenesorbitol or    dimethyldibenzylidenesorbitol (e.g. 1,3:2,4 di(methylbenzylidene)    sorbitol), or substituted nonitol-derivatives, such as    1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol,    and-   (iii) salts of diesters of phosphoric acid, e.g. sodium    2,2′-methylenebis(4, 6,-di-tert-butylphenyl)phosphate or    aluminium-hydroxy-bis[2,2′-methylene-bis(4,6-di-t-butylphenyl)phosphate],    and-   (iv) vinylcycloalkane polymer and vinylalkane polymer, and-   (v) mixtures thereof.

Such additives are generally commercially available and are described,for example, in “Plastic Additives Handbook”, 5th edition, 2001 of HansZweifel.

Preferably the propylene copolymer (R-PP) contains up to 2.0 wt.-% ofthe α-nucleating agent. In a preferred embodiment, the propylenecopolymer (R-PP) contains not more than 3000 ppm, more preferably of 1to 3000 ppm, more preferably of 5 to 2000 ppm of a α-nucleating agent,in particular selected from the group consisting ofdibenzylidenesorbitol (e.g. 1,3:2,4 dibenzylidene sorbitol),dibenzylidenesorbitol derivative, preferablydimethyldibenzylidenesorbitol (e.g. 1,3:2,4 di(methylbenzylidene)sorbitol), or substituted nonitol-derivatives, such as1,2,3,-trideoxy-4,6:5,7-bis-O-[(4-propylphenyl)methylene]-nonitol,vinylcycloalkane polymer, vinylalkane polymer, and mixtures thereof.

The present invention is also directed to injection molded articlescomprising at least 70 wt.-%, more preferably at least 90 wt.-%, yetmore preferably at least 95 wt.-%, still more preferably consisting of,a propylene copolymer (R-PP) as defined herein.

Further present invention is also directed to thin wall packagingelements, like thin wall packaging elements produced by injectionmolding, comprising at least 70 wt.-%, more preferably at least 90wt.-%, yet more preferably at least 95 wt.-%, still more preferablyconsisting of, a propylene copolymer (R-PP) as defined herein.

The thin wall packaging elements, like thin wall packaging elementsproduced by injection molding, preferably have a thickness of equal orbelow 2 mm, preferably in the range of 0.2 to 2.0 mm. Said thin wallpackaging elements are preferably produced by injection molding. Furtherthe thin wall packaging elements are preferably selected from the groupconsisting of cups, boxes, trays, pails, buckets, bowls, lids, flaps,caps, CD covers, DVD covers and the like.

The propylene copolymer (R-PP) according to this invention is preferablyproduced in a sequential polymerization process in the presence of aZiegler-Natta catalyst as defined below.

Accordingly it is preferred that the propylene copolymer (R-PP) isproduced in the presence of

-   (a) a Ziegler-Natta catalyst (ZN-C) comprises a titanium compound    (TC), a magnesium compound (MC) and an internal donor (ID), wherein    said internal donor (ID) is a non-phtalic acid ester,-   (b) optionally a co-catalyst (Co), and-   (c) optionally an external donor (ED).

Preferably the propylene copolymer (R-PP) is produced in a sequentialpolymerization process comprising at least two reactors (R1) and (R2),in the first reactor (R1) the first propylene copolymer fraction (R-PP1)is produced and subsequently transferred into the second reactor (R2),in the second reactor (R2) the second propylene copolymer fraction(R-PP2) is produced in the presence of the first propylene copolymerfraction (R-PP1).

The term “sequential polymerization system” indicates that the propylenecopolymer (R-PP) is produced in at least two reactors connected inseries. Accordingly the present polymerization system comprises at leasta first polymerization reactor (R1) and a second polymerization reactor(R2), and optionally a third polymerization reactor (R3). The term“polymerization reactor” shall indicate that the main polymerizationtakes place. Thus in case the process consists of two polymerizationreactors, this definition does not exclude the option that the overallsystem comprises for instance a pre-polymerization step in apre-polymerization reactor. The term “consist of” is only a closingformulation in view of the main polymerization reactors.

Preferably at least one of the two polymerization reactors (R1) and (R2)is a gas phase reactor (GPR). Still more preferably the secondpolymerization reactor (R2) and the optional third polymerizationreactor (R3) are gas phase reactors (GPRs), i.e. a first gas phasereactor (GPR1) and a second gas phase reactor (GPR2). A gas phasereactor (GPR) according to this invention is preferably a fluidized bedreactor, a fast fluidized bed reactor or a settled bed reactor or anycombination thereof.

Accordingly, the first polymerization reactor (R1) is preferably aslurry reactor (SR) and can be any continuous or simple stirred batchtank reactor or loop reactor operating in bulk or slurry. Bulk means apolymerization in a reaction medium that comprises of at least 60% (w/w)monomer. According to the present invention the slurry reactor (SR) ispreferably a (bulk) loop reactor (LR). Accordingly the averageconcentration of propylene copolymer (R-PP), i.e. the first fraction(1^(st) F) of the propylene copolymer (R-PP) (i.e. the first propylenecopolymer fraction (R-PP1)), in the polymer slurry within the loopreactor (LR) is typically from 15 wt.-% to 55 wt.-%, based on the totalweight of the polymer slurry within the loop reactor (LR). In onepreferred embodiment of the present invention the average concentrationof the first propylene copolymer fraction (R-PP1) in the polymer slurrywithin the loop reactor (LR) is from 20 wt.-% to 55 wt.-% and morepreferably from 25 wt.-% to 52 wt.-%, based on the total weight of thepolymer slurry within the loop reactor (LR).

Preferably the propylene copolymer of the first polymerization reactor(R1), i.e. the first propylene copolymer fraction (R-PP1), morepreferably the polymer slurry of the loop reactor (LR) containing thefirst propylene copolymer fraction (R-PP1), is directly fed into thesecond polymerization reactor (R2), i.e. into the (first) gas phasereactor (GPR1), without a flash step between the stages. This kind ofdirect feed is described in EP 887379 A, EP 887380 A, EP 887381 A and EP991684 A. By “direct feed” is meant a process wherein the content of thefirst polymerization reactor (R1), i.e. of the loop reactor (LR), thepolymer slurry comprising the first propylene copolymer fraction(R-PP1), is led directly to the next stage gas phase reactor.

Alternatively, the propylene copolymer of the first polymerizationreactor (R1), i.e. the first propylene copolymer fraction (R-PP1), morepreferably polymer slurry of the loop reactor (LR) containing the firstpropylene copolymer fraction (R-PP1), may be also directed into a flashstep or through a further concentration step before fed into the secondpolymerization reactor (R2), i.e. into the gas phase reactor (GPR).Accordingly, this “indirect feed” refers to a process wherein thecontent of the first polymerization reactor (R1), of the loop reactor(LR), i.e. the polymer slurry, is fed into the second polymerizationreactor (R2), into the (first) gas phase reactor (GPR1), via a reactionmedium separation unit and the reaction medium as a gas from theseparation unit.

More specifically, the second polymerization reactor (R2), and anysubsequent reactor, for instance the third polymerization reactor (R3),are preferably gas phase reactors (GPRs). Such gas phase reactors (GPR)can be any mechanically mixed or fluid bed reactors. Preferably the gasphase reactors (GPRs) comprise a mechanically agitated fluid bed reactorwith gas velocities of at least 0.2 m/sec. Thus it is appreciated thatthe gas phase reactor is a fluidized bed type reactor preferably with amechanical stirrer.

Thus in a preferred embodiment the first polymerization reactor (R1) isa slurry reactor (SR), like loop reactor (LR), whereas the secondpolymerization reactor (R2) and any optional subsequent reactor, likethe third polymerization reactor (R3), are gas phase reactors (GPRs).Accordingly for the instant process at least two, preferably twopolymerization reactors (R1) and (R2) or three polymerization reactors(R1), (R2) and (R3), namely a slurry reactor (SR), like loop reactor(LR) and a (first) gas phase reactor (GPR1) and optionally a second gasphase reactor (GPR2), connected in series are used. If needed prior tothe slurry reactor (SR) a pre-polymerization reactor is placed.

The Ziegler-Natta catalyst (ZN-C) is fed into the first polymerizationreactor (R1) and is transferred with the polymer (slurry) obtained inthe first polymerization reactor (R1) into the subsequent reactors. Ifthe process covers also a pre-polymerization step it is preferred thatall of the Ziegler-Natta catalyst (ZN-C) is fed in thepre-polymerization reactor. Subsequently the pre-polymerization productcontaining the Ziegler-Natta catalyst (ZN-C) is transferred into thefirst polymerization reactor (R1).

A preferred multistage process is a “loop-gas phase”-process, such asdeveloped by Borealis A/S, Denmark (known as BORSTAR® technology)described e.g. in patent literature, such as in EP 0 887 379, WO92/12182 WO 2004/000899, WO 2004/111095, WO 99/24478, WO 99/24479 or inWO 00/68315.

A further suitable slurry-gas phase process is the Spheripol® process ofBasell.

Especially good results are achieved in case the temperature in thereactors is carefully chosen.

Accordingly it is preferred that the operating temperature in the firstpolymerization reactor (R1) is in the range of 62 to 85° C., morepreferably in the range of 65 to 82° C., still more preferably in therange of 67 to 80° C.

Alternatively or additionally to the previous paragraph it is preferredthat the operating temperature in the second polymerization reactor (R2)and optional in the third reactor (R3) is in the range of 75 to 95° C.,more preferably in the range of 78 to 92° C.

Preferably the operating temperature in the second polymerizationreactor (R2) is equal or higher to the operating temperature in thefirst polymerization reactor (R1). Accordingly it is preferred that theoperating temperature

(a) in the first polymerization reactor (R1) is in the range of 62 to85° C., more preferably in the range of 65 to 82° C., still morepreferably in the range of 67 to 80° C., like 67 to 75° C., e.g. 70° C.;and(b) in the second polymerization reactor (R2) is in the range of 75 to95° C., more preferably in the range of 78 to 92° C., still morepreferably in the range of 78 to 88° C., with the proviso that theoperating temperature in the in the second polymerization reactor (R2)is equal or higher to the operating temperature in the firstpolymerization reactor (R1).

Still more preferably the operating temperature of the thirdpolymerization reactor (R3)—if present—is higher than the operatingtemperature in the first polymerization reactor (R1). In one specificembodiment the operating temperature of the third polymerization reactor(R3)—if present—is higher than the operating temperature in the firstpolymerization reactor (R1) and in the second polymerization reactor(R2). Accordingly it is preferred that the operating temperature

(a) in the first polymerization reactor (R1) is in the range of 62 to85° C., more preferably in the range of 65 to 82° C., still morepreferably in the range of 67 to 80° C., like 67 to 75° C., e.g. 70° C.;(b) in the second polymerization reactor (R2) is in the range of 75 to95° C., more preferably in the range of 78 to 92° C., still morepreferably in the range of 78 to 88° C.,and(c) in the third polymerization reactor (R3)—if present—is in the rangeof 75 to 95° C., more preferably in the range of 78 to 92° C., stillmore preferably in the range of 85 to 92° C., like in the range of 87 to92° C.,with the proviso that the operating temperature in the in the secondpolymerization reactor (R2) is equal or higher to the operatingtemperature in the first polymerization reactor (R1)andwith the proviso that the third polymerization reactor (R3) is higherthan the operating temperature in the first polymerization reactor (R1),preferably is higher than the operating temperature in the firstpolymerization reactor (R1) and in the second polymerization reactor(R2).

Typically the pressure in the first polymerization reactor (R1),preferably in the loop reactor (LR), is in the range of from 20 to 80bar, preferably 30 to 70 bar, like 35 to 65 bar, whereas the pressure inthe second polymerization reactor (R2), i.e. in the (first) gas phasereactor (GPR1), and optionally in any subsequent reactor, like in thethird polymerization reactor (R3), e.g. in the second gas phase reactor(GPR2), is in the range of from 5 to 50 bar, preferably 15 to 40 bar.

Preferably hydrogen is added in each polymerization reactor in order tocontrol the molecular weight, i.e. the melt flow rate MFR₂.

Preferably the average residence time is rather long in thepolymerization reactors (R1) and (R2). In general, the average residencetime (τ) is defined as the ratio of the reaction volume (V_(R)) to thevolumetric outflow rate from the reactor (Q_(o)) (i.e. V_(R)/Q_(o)), i.eτ=V_(R)/Q_(o) [tau=V_(R)/Q_(o)]. In case of a loop reactor the reactionvolume (V_(R)) equals to the reactor volume.

Accordingly the average residence time (τ) in the first polymerizationreactor (R1) is preferably at least 20 min, more preferably in the rangeof 20 to 80 min, still more preferably in the range of 25 to 60 min,like in the range of 28 to 50 min, and/or the average residence time (τ)in the second polymerization reactor (R2) is preferably at least 90 min,more preferably in the range of 90 to 220 min, still more preferably inthe range of 100 to 210 min, yet more preferably in the range of 105 to200 min, like in the range of 105 to 190 min Preferably the averageresidence time (τ) in the third polymerization reactor (R3)—ifpresent—is preferably at least 30 min, more preferably in the range of30 to 120 min, still more preferably in the range of 40 to 100 min, likein the range of 50 to 90 min.

Further it is preferred that the average residence time (τ) in the totalsequential polymerization system, more preferably that the averageresidence time (τ) in the first (R1) second polymerization reactors (R2)and optional third polymerization reactor (R3) together, is at least 140min, more preferably at least 160 min, still more preferably in therange of 140 to 260 min, more preferably in the range of 160 to 240 min,still more preferably in the range of 160 to 220 min, yet morepreferably in the range of 160 to 220 min.

As mentioned above the instant process can comprises in addition to the(main) polymerization of the propylene copolymer (R-PP) in the at leasttwo polymerization reactors (R1, R3 and optional R3) prior thereto apre-polymerization in a pre-polymerization reactor (PR) upstream to thefirst polymerization reactor (R1).

In the pre-polymerization reactor (PR) a polypropylene (Pre-PP) isproduced. The pre-polymerization is conducted in the presence of theZiegler-Natta catalyst (ZN-C). According to this embodiment theZiegler-Natta catalyst (ZN-C), the co-catalyst (Co), and the externaldonor (ED) are all introduced to the pre-polymerization step. However,this shall not exclude the option that at a later stage for instancefurther co-catalyst (Co) and/or external donor (ED) is added in thepolymerization process, for instance in the first reactor (R1). In oneembodiment the Ziegler-Natta catalyst (ZN-C), the co-catalyst (Co), andthe external donor (ED) are only added in the pre-polymerization reactor(PR), if a pre-polymerization is applied.

The pre-polymerization reaction is typically conducted at a temperatureof 0 to 60° C., preferably from 15 to 50° C., and more preferably from20 to 45° C.

The pressure in the pre-polymerization reactor is not critical but mustbe sufficiently high to maintain the reaction mixture in liquid phase.Thus, the pressure may be from 20 to 100 bar, for example 30 to 70 bar.

In a preferred embodiment, the pre-polymerization is conducted as bulkslurry polymerization in liquid propylene, i.e. the liquid phase mainlycomprises propylene, with optionally inert components dissolved therein.Furthermore, according to the present invention, an ethylene feed isemployed during pre-polymerization as mentioned above.

It is possible to add other components also to the pre-polymerizationstage. Thus, hydrogen may be added into the pre-polymerization stage tocontrol the molecular weight of the polypropylene (Pre-PP) as is knownin the art. Further, antistatic additive may be used to prevent theparticles from adhering to each other or to the walls of the reactor.

The precise control of the pre-polymerization conditions and reactionparameters is within the skill of the art.

Due to the above defined process conditions in the pre-polymerization,preferably a mixture (MI) of the Ziegler-Natta catalyst (ZN-C) and thepolypropylene (Pre-PP) produced in the pre-polymerization reactor (PR)is obtained. Preferably the Ziegler-Natta catalyst (ZN-C) is (finely)dispersed in the polypropylene (Pre-PP). In other words, theZiegler-Natta catalyst (ZN-C) particles introduced in thepre-polymerization reactor (PR) split into smaller fragments which areevenly distributed within the growing polypropylene (Pre-PP). The sizesof the introduced Ziegler-Natta catalyst (ZN-C) particles as well as ofthe obtained fragments are not of essential relevance for the instantinvention and within the skilled knowledge.

As mentioned above, if a pre-polymerization is used, subsequent to saidpre-polymerization, the mixture (MI) of the Ziegler-Natta catalyst(ZN-C) and the polypropylene (Pre-PP) produced in the pre-polymerizationreactor (PR) is transferred to the first reactor (R1). Typically thetotal amount of the polypropylene (Pre-PP) in the final propylenecopolymer (R-PP) is rather low and typically not more than 5.0 wt.-%,more preferably not more than 4.0 wt.-%, still more preferably in therange of 0.5 to 4.0 wt.-%, like in the range 1.0 of to 3.0 wt.-%.

In case that pre-polymerization is not used propylene and the otheringredients such as the Ziegler-Natta catalyst (ZN-C) are directlyintroduced into the first polymerization reactor (R1).

Accordingly the process according the instant invention comprises thefollowing steps under the conditions set out above

(a) in the first polymerization reactor (R1), i.e. in a loop reactor(LR), propylene and a comonomer being ethylene and/or a C₄ to C₁₂α-olefin, preferably propylene and ethylene, are polymerized obtaining afirst propylene copolymer fraction (R-PP1) of the propylene copolymer(R-PP),(b) transferring said first propylene copolymer fraction (R-PP1) to asecond polymerization reactor (R2),(c) in the second polymerization reactor (R2) propylene and a comonomerbeing ethylene and/or a C₄ to C₁₂ α-olefin, preferably propylene andethylene, are polymerized in the presence of the first propylenecopolymer fraction (R-PP1) obtaining a second propylene copolymerfraction (R-PP2) of the propylene copolymer (R-PP), said first propylenecopolymer fraction (R-PP1) and said second propylene copolymer fraction(R-PP2) form the propylene copolymer (R-PP).

A pre-polymerization as described above can be accomplished prior tostep (a).

The Ziegler-Natta Catalyst (ZN-C), the External Donor (ED) and theCo-Catalyst (Co)

As pointed out above in the specific process for the preparation of thepropylene copolymer (R-PP) as defined above a Ziegler-Natta catalyst(ZN-C) must be used. Accordingly the Ziegler-Natta catalyst (ZN-C) willbe now described in more detail.

The catalyst used in the present invention is a solid Ziegler-Nattacatalyst (ZN-C), which comprises a titanium compound (TC), a magnesiumcompound (MC) and an internal donor (ID), wherein said internal donor(ID) is a non-phthalic acid ester, most preferably diester ofnon-phthalic dicarboxylic acids as described in more detail below. Thus,the catalyst used in the present invention is fully free of undesiredphthalic compounds.

The Ziegler-Natta catalyst (ZN-C) can be further defined by the way asobtained. Accordingly the Ziegler-Natta catalyst (ZN-C) is preferablyobtained by a process comprising the steps of

-   a) providing a solution of at least one complex (A) being a complex    of a magnesium compound (MC) and an alcohol comprising in addition    to the hydroxyl moiety at least one further oxygen bearing moiety    (A1) being different to a hydroxyl group, and optionally at least    one complex (B) being a complex of said magnesium compound (MC) and    an alcohol not comprising any other oxygen bearing moiety (B1),-   b) combining said solution with a titanium compound (TC) and    producing an emulsion the dispersed phase of which contains more    than 50 mol.-% of the magnesium;-   c) agitating the emulsion in order to maintain the droplets of said    dispersed phase preferably within an average size range of 5 to 200    μm;-   d) solidifying said droplets of the dispersed phase;-   e) recovering the solidified particles of the olefin polymerisation    catalyst component,    and wherein an internal donor (ID) is added at any step prior to    step c) and said internal donor (ID) is non-phthalic acid ester,    preferably said internal donor (ID) is a diester of non-phthalic    dicarboxylic acids as described in more detail below.

Detailed description as to how such a Ziegler-Natta catalyst (ZN-C) canbe obtained is disclosed in WO 2012/007430.

In a preferred embodiment in step a) the solution of complex ofmagnesium compound (MC) is a mixture of complexes of magnesium compound(MC) (complexes (A) and (B)).

The complexes of magnesium compound (MC) (complexes (A) and (B)) can beprepared in situ in the first step of the catalyst preparation processby reacting said magnesium compound (MC) with the alcohol(s) asdescribed above and in more detail below, or said complexes can beseparately prepared complexes, or they can be even commerciallyavailable as ready complexes and used as such in the catalystpreparation process of the invention. In case the mixture of complexesof magnesium compound (MC) (complexes (A) and (B)) are prepared in situin the first step of the catalyst preparation process they arepreferably prepared by reacting said magnesium compound (MC) with themixture of alcohols (A1) and (B1).

Preferably, the alcohol (A1) comprising in addition to the hydroxylmoiety at least one further oxygen bearing group different to a hydroxylgroup to be employed in accordance with the present invention is analcohol bearing an ether group.

Illustrative examples of such preferred alcohols (A1) comprising inaddition to the hydroxyl moiety at least one further oxygen bearinggroup to be employed in accordance with the present invention are glycolmonoethers, in particular C₂ to C₄ glycol monoethers, such as ethyleneor propylene glycol monoethers wherein the ether moieties comprise from2 to 18 carbon atoms, preferably from 4 to 12 carbon atoms. Preferredmonoethers are C₂ to C₄ glycol monoethers and derivatives thereof.Illustrative and preferred examples are 2-(2-ethylhexyloxy)ethanol,2-butyloxy ethanol, 2-hexyloxy ethanol and1,3-propylene-glycol-monobutyl ether, 3-butoxy-2-propanol, with2-(2-ethylhexyloxy)ethanol and 1,3-propylene-glycol-monobutyl ether,3-butoxy-2-propanol being particularly preferred.

In case a mixture of complexes (A) and (B) (or alcohols (A1) and (B1)respectively) are used, the different complexes or alcohols are usuallyemployed in a mole ratio of A:B, or A1:B1 from 1.0:10 to 1.0:0.5,preferably this mole ratio is from 1.0:8.0 to 1.0:1.0, more preferably1.0:6.0 to 1.0:2.0, even more preferably 1.0:5.0 to 1.0:3.0. Asindicated in the ratios above it is more preferred that the amount ofalcohol A1, preferably alcohol with ether moiety, is higher that alcoholB1, i.e. alcohol without any other oxygen bearing moiety different tohydroxyl.

The internal donor (ID) used in the preparation of the Ziegler-Nattacatalyst (ZN-C) is preferably selected from (di)esters of non-phthaliccarboxylic (di)acids and derivatives and mixtures thereof. The estermoieties, i.e. the moieties derived from an alcohol (i.e. the alkoxygroup of the ester), may be identical or different, preferably theseester moieties are identical. Typically the ester moieties are aliphaticor aromatic hydrocarbon groups. Preferred examples thereof are linear orbranched aliphatic groups having from 1 to 20 carbon atoms, preferably 2to 16 carbon atoms, more preferably from 2 to 12 carbon atoms, oraromatic groups having 6 to 12 carbon atoms, optionally containingheteroatoms of Groups 14 to 17 of the Periodic Table of IUPAC,especially N, O, S and/or P. The acid moiety of the di- ormonoacid(di)ester, preferably of the diester of diacid, preferablycomprises 1 to 30 carbon atoms, more preferably, 2 to 20 carbon atoms,still more preferably 2 to 16 carbon atoms, optionally being substitutedby aromatic or saturated or non-saturated cyclic or aliphatichydrocarbyls having 1 to 20 C, preferably 1 to 10 carbon atoms andoptionally containing heteroatoms of Groups 14 to 17 of the PeriodicTable of IUPAC, especially N, O, S and/or P. Especially preferred estersare diesters of mono-unsaturated dicarboxylic acids.

In particular preferred esters are esters belonging to a groupcomprising malonates, maleates, succinates, glutarates,cyclohexene-1,2-dicarboxylates and benzoates, optionally beingsubstituted as defined below, and any derivatives and/or mixturesthereof. Preferred examples are e.g. substituted maleates andcitraconates, most preferably citraconates.

The internal donor (ID) or precursor thereof as defined further below isadded preferably in step a) to said solution.

Esters used as internal donors (ID) can be prepared as is well known inthe art. As example dicarboxylic acid diesters can be formed by simplyreacting of a carboxylic diacid anhydride with a C₁-C₂₀ alkanol and/ordiol.

The titanium compound (TC) is preferably a titanium halide, like TiCl₄.

The complexes of magnesium compounds can be alkoxy magnesium complexes,preferably selected from the group consisting of magnesium dialkoxides,and complexes of a magnesium dihalide and a magnesium dialkoxide. It maybe a reaction product of an alcohol and a magnesium compound selectedfrom the group consisting of dialkyl magnesiums, alkyl magnesiumalkoxides and alkyl magnesium halides, preferably dialkyl magnesium. Itcan further be selected from the group consisting of dialkyloxymagnesiums, diaryloxy magnesiums, alkyloxy magnesium halides, aryloxymagnesium halides, alkyl magnesium alkoxides, aryl magnesium alkoxidesand alkyl magnesium aryloxides.

The magnesium dialkoxide may be the reaction product of a dialkylmagnesium of the formula R₂Mg, wherein each one of the two Rs is asimilar or different C₁-C₂₀ alkyl, preferably a similar or differentC₂-C₁₀ alkyl with alcohols as defined in the present application.Typical magnesium alkyls are ethylbutyl magnesium, dibutyl magnesium,dipropyl magnesium, propylbutyl magnesium, dipentyl magnesium,butylpentyl magnesium, butyloctyl magnesium and dioctyl magnesium. Mostpreferably, one R of the formula R₂Mg is a butyl group and the other Ris an octyl or ethyl group, i.e. the dialkyl magnesium compound is butyloctyl magnesium or butyl ethyl magnesium.

Typical alkyl-alkoxy magnesium compounds RMgOR, when used, are ethylmagnesium butoxide, butyl magnesium pentoxide, octyl magnesium butoxideand octyl magnesium octoxide.

Dialkyl magnesium or alkyl magnesium alkoxide can react, in addition tothe alcohol containing in addition to the hydroxyl group at least onefurther oxygen bearing moiety being different to a hydroxyl moiety,which is defined above in this application, with a monohydric alcoholR′OH, or a mixture thereof with a polyhydric alcohol R′(OH)_(m)

Preferred monohydric alcohols are alcohols of the formula R^(b)(OH),wherein R^(b) is a C₁-C₂₀, preferably a C₄-C₁₂, and most preferably aC₆-C₁₀, straight-chain or branched alkyl residue or a C₆-C₁₂ arylresidue. Preferred monohydric alcohols include methanol, ethanol,n-propanol, iso-propanol, n-butanol, iso-butanol, sec-butanol,tert-butanol, n-amyl alcohol, iso-amyl alcohol, sec-amyl alcohol,tert-amyl alcohol, diethyl carbinol, sec-isoamyl alcohol, tert-butylcarbinol, 1-hexanol, 2-ethyl-1-butanol, 4-methyl-2-pentanol, 1-heptanol,2-heptanol, 4-heptanol, 2,4-dimethyl-3-pentanol, 1-octanol, 2-octanol,2-ethyl-1-hexanol, 1-nonanol, 5-nonanol, diisobutyl carbinol, 1-decanoland 2,7-dimethyl-2-octanol, 1-undecanol, 1-dodecanol, 1-tridecanol,1-tetradecanol, 1-pentadecanol, 1-hexadecanol, 1-heptadecanol1-octadecanol and phenol or benzyl alcohol. The aliphatic monohydricalcohols may optionally be unsaturated, as long as they do not act ascatalyst poisons. The most preferred monohydric alcohol is2-ethyl-1-hexanol.

Preferred polyhydric alcohols are alcohols of the formula R^(a)(OH)_(m),wherein R^(a) is a straight-chain, cyclic or branched C₂ to C₆hydrocarbon residue, (OH) denotes hydroxyl moieties of the hydrocarbonresidue and m is an integer of 2 to 6, preferably 3 to 5. Especiallypreferred polyhydric alcohols include ethylene glycol, propylene glycol,trimethylene glycol, 1,2-butylene glycol, 1,3-butylene glycol,1,4-butylene glycol, 2,3-butylene glycol, 1,5pentanediol,1,6-hexanediol, 1,8-octanediol, pinacol, diethylene glycol, triethyleneglycol, 1,2-catechol, 1,3-catechol and 1,4-catechol, and triols such asglycerol and pentaerythritol.

The solvents to be employed for the preparation of the Ziegler-Nattacatalyst (ZN-C) may be selected among aromatic and aliphatic solvents ormixtures thereof. Preferably the solvents are aromatic and/or aliphatichydrocarbons with 5 to 20 carbon atoms, preferably 5 to 16, morepreferably 5 to 12 carbon atoms, examples of which include benzene,toluene, cumene, xylol and the like, with toluene being preferred, aswell as pentane, hexane, heptane, octane and nonane including straightchain, branched and cyclic compounds, and the like, with hexanes andheptanes being particular preferred.

Mg compound (MC) is typically provided as a 10 to 50 wt-% solution in asolvent as indicated above. Typical commercially available MC solutionsare 20-40 wt-% solutions in toluene or heptanes.

The reaction for the preparation of the complex of magnesium compound(MC) may be carried out at a temperature of 40° to 70° C.

In step b) the solution of step a) is typically added to the titaniumcompound (TC), such as titanium tetrachloride. This addition preferablyis carried out at a low temperature, such as from −10 to 40° C.,preferably from −5 to 20° C., such as about −5° C. to 15° C.

The temperature for steps b) and c), is typically −10 to 50° C.,preferably from −5 to 30° C., while solidification typically requiresheating as described in detail further below.

The emulsion, i.e. the two phase liquid-liquid system may be formed inall embodiments of the present invention by simple stirring andoptionally adding (further) solvent(s) and additives, such as theturbulence minimizing agent (TMA) and/or the emulsifying agentsdescribed further below.

Preparation of the Ziegler-Natta catalyst (ZN-C) used in the presentinvention is based on a liquid/liquid two-phase system where no separateexternal carrier materials such as silica or MgCl₂ are needed in orderto get solid catalyst particles.

The present Ziegler-Natta catalyst (ZN-C) particles are spherical andthey have preferably a mean particle size from 5 to 500 μm, such as from5 to 300 μm and in embodiments from 5 to 200 μm, or even from 10 to 100μm. These ranges also apply for the droplets of the dispersed phase ofthe emulsion as described herein, taking into consideration that thedroplet size can change (decrease) during the solidification step.

The process of the preparation of the Ziegler-Natta catalyst (ZN-C) asintermediate stage, yields to an emulsion of a denser, titanium compound(TC)/toluene-insoluble, oil dispersed phase typically having a titaniumcompound (TC)/magnesium mol ratio of 0.1 to 10 and an oil disperse phasehaving a titanium compound (TC)/magnesium mol ratio of 10 to 100. Thetitanium compound (TC) is preferably TiCl₄. This emulsion is thentypically agitated, optionally in the presence of an emulsion stabilizerand/or a turbulence minimizing agent, in order to maintain the dropletsof said dispersed phase, typically within an average size range of 5 to200 μm. The catalyst particles are obtained after solidifying saidparticles of the dispersed phase e.g. by heating.

In effect, therefore, virtually the entirety of the reaction product ofthe Mg complex with the titanium compound (TC)—which is the precursor ofthe ultimate catalyst component—becomes the dispersed phase, andproceeds through the further processing steps to the final particulateform. The disperse phase, still containing a useful quantity of titaniumcompound (TC), can be reprocessed for recovery of that metal.

Furthermore, emulsifying agents/emulsion stabilizers can be usedadditionally in a manner known in the art for facilitating the formationand/or stability of the emulsion. For the said purposes e.g.surfactants, e.g. a class based on acrylic or methacrylic polymers canbe used.

Preferably, said emulsion stabilizers are acrylic or methacrylicpolymers, in particular those with medium sized ester side chains havingmore than 10, preferably more than 12 carbon atoms and preferably lessthan 30, and preferably 12 to 20 carbon atoms in the ester side chain.Particular preferred are unbranched C₁₂ to C₂₀ (meth)acrylates such aspoly(hexadecyl)-methacrylate and poly(octadecyl)-methacrylate.

Furthermore, in some embodiments a turbulence minimizing agent (TMA) canbe added to the reaction mixture in order to improve the emulsionformation and maintain the emulsion structure. Said TMA agent has to beinert and soluble in the reaction mixture under the reaction conditions,which means that polymers without polar groups are preferred, likepolymers having linear or branched aliphatic carbon backbone chains.Said TMA is in particular preferably selected from α-olefin polymers ofα-olefin monomers with 6 to 20 carbon atoms, like polyoctene,polynonene, polydecene, polyundecene or polydodecene or mixturesthereof. Most preferable it is polydecene.

TMA can be added to the emulsion in an amount of e.g. 1 to 1.000 ppm,preferably 5 to 100 ppm and more preferable 5 to 50 ppm, based on thetotal weight of the reaction mixture.

It has been found that the best results are obtained when the titaniumcompound (TC)/Mg mol ratio of the dispersed phase (denser oil) is 1 to5, preferably 2 to 4, and that of the disperse phase oil is 55 to 65.Generally the ratio of the mol ratio titanium compound (TC)/Mg in thedisperse phase oil to that in the denser oil is at least 10.

Solidification of the dispersed phase droplets by heating is suitablycarried out at a temperature of 70 to 150° C., usually at 80 to 110° C.,preferably at 90 to 110° C. The heating may be done faster or slower. Asespecial slow heating is understood here heating with a heating rate ofabout 5° C./min or less, and especial fast heating e.g. 10° C./min ormore. Often slower heating rates are preferable for obtaining goodmorphology of the catalyst component.

The solidified particulate product may be washed at least once,preferably at least twice, most preferably at least three times with ahydrocarbon, which preferably is selected from aromatic and aliphatichydrocarbons, preferably with toluene, heptane or pentane. Washings canbe done with hot (e.g. 90° C.) or cold (room temperature) hydrocarbonsor combinations thereof.

Finally, the washed Ziegler-Natta catalyst (ZN-C) is recovered. It canfurther be dried, as by evaporation or flushing with nitrogen, or it canbe slurried to an oily liquid without any drying step.

The finally obtained Ziegler-Natta catalyst (ZN-C) is desirably in theform of particles having generally an average size range of 5 to 200 μm,preferably 10 to 100, even an average size range of 20 to 60 μm ispossible.

The Ziegler-Natta catalyst (ZN-C) is preferably used in association withan alkyl aluminum cocatalyst and optionally external donors.

As further component in the instant polymerization process an externaldonor (ED) is preferably present. Suitable external donors (ED) includecertain silanes, ethers, esters, amines, ketones, heterocyclic compoundsand blends of these. It is especially preferred to use a silane. It ismost preferred to use silanes of the general formula

R^(a) _(p)R^(b) _(q)Si(OR^(c))_((4-p-q))

wherein R^(a), R^(b) and R^(c) denote a hydrocarbon radical, inparticular an alkyl or cycloalkyl group, and wherein p and q are numbersranging from 0 to 3 with their sum p+q being equal to or less than 3.R^(a), R^(b) and R^(c) can be chosen independently from one another andcan be the same or different. Specific examples of such silanes are(tert-butyl)₂Si(OCH₃)₂, (cyclohexyl)(methyl)Si(OCH₃)²,(phenyl)₂Si(OCH₃)₂ and (cyclopentyl)₂Si(OCH₃)₂, or of general formula

Si(OCH₂CH₃)₃(NR³R⁴)

wherein R³ and R⁴ can be the same or different a represent a hydrocarbongroup having 1 to 12 carbon atoms.

R³ and R⁴ are independently selected from the group consisting of linearaliphatic hydrocarbon group having 1 to 12 carbon atoms, branchedaliphatic hydrocarbon group having 1 to 12 carbon atoms and cyclicaliphatic hydrocarbon group having 1 to 12 carbon atoms. It is inparticular preferred that R³ and R⁴ are independently selected from thegroup consisting of methyl, ethyl, n-propyl, n-butyl, octyl, decanyl,iso-propyl, iso-butyl, iso-pentyl, tert.-butyl, tert.-amyl, neopentyl,cyclopentyl, cyclohexyl, methylcyclopentyl and cycloheptyl.

More preferably both R¹ and R² are the same, yet more preferably both R³and R⁴ are an ethyl group.

In addition to the Ziegler-Natta catalyst (ZN-C) and the optionalexternal donor (ED) a co-catalyst can be used. The co-catalyst ispreferably a compound of group 13 of the periodic table (IUPAC), e.g.organo aluminum, such as an aluminum compound, like aluminum alkyl,aluminum halide or aluminum alkyl halide compound. Accordingly in onespecific embodiment the co-catalyst (Co) is a trialkylaluminium, liketriethylaluminium (TEAL), dialkyl aluminium chloride or alkyl aluminiumdichloride or mixtures thereof. In one specific embodiment theco-catalyst (Co) is triethylaluminium (TEAL).

Advantageously, the triethyl aluminium (TEAL) has a hydride content,expressed as AlH₃, of less than 1.0 wt % with respect to the triethylaluminium (TEAL). More preferably, the hydride content is less than 0.5wt %, and most preferably the hydride content is less than 0.1 wt %.

Preferably the ratio between the co-catalyst (Co) and the external donor(ED) [Co/ED] and/or the ratio between the co-catalyst (Co) and thetransition metal (TM) [Co/TM] should be carefully chosen.

Accordingly

(a) the mol-ratio of co-catalyst (Co) to external donor (ED) [Co/ED]must be in the range of 5 to 45, preferably is in the range of 5 to 35,more preferably is in the range of 5 to 25, still more preferably is inthe range of 5 to 20; and optionally(b) the mol-ratio of co-catalyst (Co) to titanium compound (TC) [Co/TC]must be in the range of above 80 to 500, preferably is in the range of120 to 300, still more preferably is in the range of 140 to 200.

In the following the present invention is further illustrated by meansof examples.

EXAMPLES 1. Measuring Methods

The following definitions of terms and determination methods apply forthe above general description of the invention as well as to the belowexamples unless otherwise defined.

Calculation of comonomer content of the second propylene copolymerfraction (R-PP2):

$\begin{matrix}{\frac{{C({PP})} - {{w\left( {{PP}\; 1} \right)} \times {C\left( {{PP}\; 1} \right)}}}{w\left( {{PP}\; 2} \right)} = {C\left( {{PP}\; 2} \right)}} & (I)\end{matrix}$

wherein

-   w(PP1) is the weight fraction [in wt.-%] of the first propylene    copolymer fraction (R-PP1),-   w(PP2) is the weight fraction [in wt.-%] of second propylene    copolymer fraction (R-PP2),-   C(PP1) is the comonomer content [in mol-%] of the first random    propylene copolymer fraction (R-PP1),-   C(PP) is the comonomer content [in mol-%] of the random propylene    copolymer (R-PP),-   C(PP2) is the calculated comonomer content [in mol-%] of the second    random propylene copolymer fraction (R-PP2).    Calculation of melt flow rate MFR₂ (230° C.) of the second propylene    copolymer fraction (R-PP2):

$\begin{matrix}{{{MFR}\left( {{PP}\; 2} \right)} = 10^{\lbrack\frac{{\log {({{MFR}{({PP})}})}} - {{w{({{PP}\; 1})}} \times {\log {({{MFR}{({{PP}\; 1})}})}}}}{w{({{PP}\; 2})}}\rbrack}} & ({III})\end{matrix}$

wherein

-   w(PP1) is the weight fraction [in wt.-%] of the first propylene    copolymer fraction (R-PP1),-   w(PP2) is the weight fraction [in wt.-%] of second propylene    copolymer fraction (R-PP2),-   MFR(PP1) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    first propylene copolymer fraction (R-PP1),-   MFR(PP) is the melt flow rate MFR₂ (230° C.) [in g/10 min] of the    propylene copolymer (R-PP),-   MFR(PP2) is the calculated melt flow rate MFR₂ (230° C.) [in g/10    min] of the second propylene copolymer fraction (R-PP2).-   MFR₂ (230° C.) is measured according to ISO 1133 (230° C., 2.16 kg    load).

Quantification of Microstructure by NMR Spectroscopy

Quantitative nuclear-magnetic resonance (NMR) spectroscopy was used toquantify the comonomer content and comonomer sequence distribution ofthe polymers. Quantitative ¹³C{¹H} NMR spectra were recorded in thesolution-state using a Bruker Advance III 400 NMR spectrometer operatingat 400.15 and 100.62 MHz for ¹H and ¹³C respectively. All spectra wererecorded using a ¹³C optimised 10 mm extended temperature probehead at125° C. using nitrogen gas for all pneumatics. Approximately 200 mg ofmaterial was dissolved in 3 ml of 1,2-tetrachloroethane-d₂ (TCE-d₂)along with chromium-(III)-acetylacetonate (Cr(acac)₃) resulting in a 65mM solution of relaxation agent in solvent (Singh, G., Kothari, A.,Gupta, V., Polymer Testing 28 5 (2009), 475). To ensure a homogenoussolution, after initial sample preparation in a heat block, the NMR tubewas further heated in a rotatary oven for at least 1 hour. Uponinsertion into the magnet the tube was spun at 10 Hz. This setup waschosen primarily for the high resolution and quantitatively needed foraccurate ethylene content quantification. Standard single-pulseexcitation was employed without NOE, using an optimised tip angle, 1 srecycle delay and a bi-level WALTZ16 decoupling scheme (Zhou, Z.,Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D.Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere,P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol.Rapid Commun. 2007, 28, 1128). A total of 6144 (6 k) transients wereacquired per spectra. Quantitative ¹³C{¹H} NMR spectra were processed,integrated and relevant quantitative properties determined from theintegrals using proprietary computer programs. All chemical shifts wereindirectly referenced to the central methylene group of the ethyleneblock (EEE) at 30.00 ppm using the chemical shift of the solvent. Thisapproach allowed comparable referencing even when this structural unitwas not present. Characteristic signals corresponding to theincorporation of ethylene were observed Cheng, H. N., Macromolecules 17(1984), 1950).

With characteristic signals corresponding to 2,1 erythro regio defectsobserved (as described in L. Resconi, L. Cavallo, A. Fait, F.Piemontesi, Chem. Rev. 2000, 100 (4), 1253, in Cheng, H. N.,Macromolecules 1984, 17, 1950, and in W-J. Wang and S. Zhu,Macromolecules 2000, 33 1157) the correction for the influence of theregio defects on determined properties was required. Characteristicsignals corresponding to other types of regio defects were not observed.

The comonomer fraction was quantified using the method of Wang et. al.(Wang, W-J., Zhu, S., Macromolecules 33 (2000), 1157) throughintegration of multiple signals across the whole spectral region in the¹³C {¹H} spectra. This method was chosen for its robust nature andability to account for the presence of regio-defects when needed.Integral regions were slightly adjusted to increase applicability acrossthe whole range of encountered comonomer contents.

For systems where only isolated ethylene in PPEPP sequences was observedthe method of Wang et. al. was modified to reduce the influence ofnon-zero integrals of sites that are known to not be present. Thisapproach reduced the overestimation of ethylene content for such systemsand was achieved by reduction of the number of sites used to determinethe absolute ethylene content to:

E=0.5(Sββ+Sβγ+Sβδ+0.5(Sαβ+Sαγ))

Through the use of this set of sites the corresponding integral equationbecomes:

E=0.5(I _(H) +I _(G)+0.5(I _(C) +I _(D)))

using the same notation used in the article of Wang et. al. (Wang, W-J.,Zhu, S., Macromolecules 33 (2000), 1157). Equations used for absolutepropylene content were not modified.

The mole percent comonomer incorporation was calculated from the molefraction:

E [mol %]=100*fE

The weight percent comonomer incorporation was calculated from the molefraction:

E [wt %]=100*(fE*28.06)/((fE*28.06)+((1−fE)*42.08))

The comonomer sequence distribution at the triad level was determinedusing the analysis method of Kakugo et al. (Kakugo, M., Naito, Y.,Mizunuma, K., Miyatake, T. Macromolecules 15 (1982) 1150). This methodwas chosen for its robust nature and integration regions slightlyadjusted to increase applicability to a wider range of comonomercontents.

The relative content of isolated to block ethylene incorporation wascalculated from the triad sequence distribution using the followingrelationship (equation (I)):

$\begin{matrix}{{I(E)} = {\frac{f\; {PEP}}{\left( {{f\; {EEE}} + {f\; {PEE}} + {f\; {PEP}}} \right)} \times 100}} & (I)\end{matrix}$

whereinI(E) is the relative content of isolated to block ethylene sequences [in%];fPEP is the mol fraction of propylene/ethylene/propylene sequences (PEP)in the sample;fPEE is the mol fraction of propylene/ethylene/ethylene sequences (PEE)and of ethylene/ethylene/propylene sequences (EEP) in the sample;fEEE is the mol fraction of ethylene/ethylene/ethylene sequences (EEE)in the sampleBulk density, BD, is measured according ASTM D 1895

Particle Size Distribution, PSD

Coulter Counter LS 200 at room temperature with heptane as medium.

The xylene solubles (XCS, wt.-%): Content of xylene cold solubles (XCS)is determined at 25° C. according ISO 16152; first edition; 2005-07-01

The hexane extractable fraction is determined according to FDA method(federal registration, title 21, Chapter 1, part 177, section 1520, s.Annex B) on cast films of 100 μm thickness produced on a monolayer castfilm line with a melt temperature of 220° C. and a chill rolltemperature of 20° C. The extraction was performed at a temperature of50° C. and an extraction time of 30 min.

Number average molecular weight (M_(n)), weight average molecular weight(M_(w)) and polydispersity (Mw/Mn)are determined by Gel Permeation Chromatography (GPC) according to thefollowing method:

The weight average molecular weight Mw and the polydispersity (Mw/Mn),wherein Mn is the number average molecular weight and Mw is the weightaverage molecular weight) is measured by a method based on ISO16014-1:2003 and ISO 16014-4:2003. A Waters Alliance GPCV 2000instrument, equipped with refractive index detector and onlineviscosimeter was used with 3×TSK-gel columns (GMHXL-HT) from TosoHaasand 1,2,4-trichlorobenzene (TCB, stabilized with 200 mg/L 2,6-Di tertbutyl-4-methyl-phenol) as solvent at 145° C. and at a constant flow rateof 1 mL/min. 216.5 μL of sample solution were injected per analysis. Thecolumn set was calibrated using relative calibration with 19 narrow MWDpolystyrene (PS) standards in the range of 0.5 kg/mol to 11 500 kg/moland a set of well characterized broad polypropylene standards. Allsamples were prepared by dissolving 5-10 mg of polymer in 10 mL (at 160°C.) of stabilized TCB (same as mobile phase) and keeping for 3 hourswith continuous shaking prior sampling in into the GPC instrument.

DSC analysis, melting temperature (T_(m)) and heat of fusion (H_(f)),crystallization temperature (T_(c)) and heat of crystallization (H_(c)):measured with a TA Instrument Q2000 differential scanning calorimetry(DSC) on 5 to 7 mg samples. DSC is run according to ISO 11357/part3/method C2 in a heat/cool/heat cycle with a scan rate of 10° C./min inthe temperature range of −30 to +225° C. Crystallization temperature andheat of crystallization (H_(c)) are determined from the cooling step,while melting temperature and heat of fusion (H_(f)) are determined fromthe second heating step.The glass transition temperature Tg is determined by dynamic mechanicalanalysis according to ISO 6721-7. The measurements are done in torsionmode on compression moulded samples (40×10×1 mm³) between −100° C. and+150° C. with a heating rate of 2° C./min and a frequency of 1 Hz.Flexural Modulus: The flexural modulus was determined in 3-point-bendingat 23° C. according to ISO 178 on 80×10×4 mm₃ test bars injectionmoulded in line with EN ISO 1873-2.Charpy impact test: The Charpy notched impact strength (NIS) wasmeasured according to ISO 179 1eA at +23° C., using injection molded bartest specimens of 80×10×4 mm³ prepared in accordance with ISO 294-1:1996Puncture energy was determined in the instrumental falling weight (IFW)test according to ISO 6603-2 using injection moulded plaques of 60×60×2mm and a test speed of 2.2 m/s. Puncture energy reported results from anintegral of the failure energy curve measured at +23° C.The Top load test was performed by compression between two platesattached to a universal testing machine with a test speed of 10 mm/minaccording to an internal procedure in general agreement with ASTM D642.For testing, the cup is placed upside down (i.e. with the bottom facingthe moving plate) into the test setup and compressed to the point ofcollapse which is noticed by a force drop on the force-deformationcurve, for which the maximum force is noted. At least 8 cups are testedto determine an average result.

Transparency, Clarity, and Haze Measurement on Cups

Instrument: Haze-gard plus from BYK-GardnerTesting: according to ASTM D1003 (as for injection molded plates)Method: The measurement is done on the outer wall of the cups asproduced below. The top and bottom of the cups are cut off. Theresulting round wall is then split in two, horizontally. Then from thiswall six equal samples of app. 60×60 mm are cut from close to themiddle. The specimens are placed into the instrument with their convexside facing the haze port. Then the transparency, haze and clarity aremeasured for each of the six samples and the haze value is reported asthe average of these six parallels.

Preparation of 840 ml Cups

With the polymers as defined below cups are produced by injectionmolding using an Engel speed 180 machine with a 35 mm barrier screw(supplied by Engel Austria GmbH). The melt temperature was adjusted to245° C. and the mould temperature to 10° C.; an injection speed of 770cm³/s with an injection time of 0.08 s was used, followed by a holdingpressure time of 0.1 s with 1300 bar (decreasing to 800 bar) and acooling time of 1.5 s, giving a standard cycle time of 3.8 s. Thedimensions of the cup are as follows: Height 100 mm, diameter top 115mm, diameter bottom 95 mm, bottom wall thickness 0.44 mm, side-wallthickness 0.40 mm. For the cycle time optimization the machine was runwith standard injection parameters first. The machine was run in fullautomatic mode, reducing the cooling time after a stabilization time of5 minutes from 1.5 to 0.3 sec. Depending on the material behaviour thecups were then either deformed or could not get de-moulded. Then thecooling time was increased in steps of 0.1 s until the part quality wasfound to be optically and mechanically satisfactory. The cycle timeresulting from this experiment can be found in table 2.

2. Examples

The catalyst used in the polymerization process for the propylenecopolymer of the inventive examples (IE1) and (IE2) was produced asfollows:

Used Chemicals:

20% solution in toluene of butyl ethyl magnesium (Mg(Bu)(Et), BEM),provided by Chemtura2-ethylhexanol, provided by Amphochem3-Butoxy-2-propanol—(DOWANOL™ PnB), provided by Dowbis(2-ethylhexyl)citraconate, provided by SynphaBaseTiCl₄, provided by Millenium ChemicalsToluene, provided by AspokemViscoplex® 1-254, provided by EvonikHeptane, provided by Chevron

Preparation of a Mg Complex

First a magnesium alkoxide solution was prepared by adding, withstirring (70 rpm), into 11 kg of a 20 wt-% solution in toluene of butylethyl magnesium (Mg(Bu)(Et), BEM), a mixture of 4.7 kg of 2-ethylhexanoland 1.2 kg of butoxypropanol in a 20 l stainless steel reactor. Duringthe addition the reactor contents were maintained below 45° C. Afteraddition was completed, mixing (70 rpm) of the reaction mixture wascontinued at 60° C. for 30 minutes. After cooling to room temperature2.3 kg g of the donor bis(2-ethylhexyl)citraconate was added to theMg-alkoxide solution keeping temperature below 25° C. Mixing wascontinued for 15 minutes under stirring (70 rpm)

Preparation of Solid Catalyst Component

20.3 kg of TiCl₄ and 1.1 kg of toluene were added into a 20 l stainlesssteel reactor. Under 350 rpm mixing and keeping the temperature at 0°C., 14.5 kg of the Mg complex prepared in example 1 was added during 1.5hours. 1.7 l of Viscoplex® 1-254 and 7.5 kg of heptane were added andafter 1 hour mixing at 0° C. the temperature of the formed emulsion wasraised to 90° C. within 1 hour. After 30 minutes mixing was stoppedcatalyst droplets were solidified and the formed catalyst particles wereallowed to settle. After settling (1 hour), the supernatant liquid wassiphoned away.

Then the catalyst particles were washed with 45 kg of toluene at 90° C.for 20 minutes followed by two heptane washes (30 kg, 15 min) During thefirst heptane wash the temperature was decreased to 50° C. and duringthe second wash to room temperature.

The solid catalyst component was used along with triethyl-aluminium(TEAL) as co-catalyst and dicyclo pentyl dimethoxy silane (D-donor) asdonor.

The catalyst used in the polymerization processes of the comparativeexample (CE1) was the catalyst of the example section of WO 2010009827A1 (see pages 30 and 31) along with triethyl-aluminium (TEAL) asco-catalyst and dicyclo pentyl dimethoxy silane (D-donor) as donor.

The aluminium to donor ratio, the aluminium to titanium ratio and thepolymerization conditions are indicated in table 1.

TABLE 1 Preparation of the Examples IE1 IE2 CE1 TEAL/Ti [mol/mol] 171145 150 TEAL/Donor [mol/mol] 6.1 6.1 4.0 Loop (R-PP1) Time [h] 0.74 0.760.50 Temperature [° C.] 70 70 75 MFR₂ [g/10 min] 33.0 43.0 45.0 XCS[wt.-%] 8.2 7.5 5.5 C2 content [mol-%] 4.6 4.0 4.1 H₂/C3 ratio[mol/kmol] 4.77 5.46 6.55 C2/C3 ratio [mol/kmol] 7.96 8.11 9.01 amount[wt.-%] 52 47 45 1 GPR (R-PP2) Time [h] 2.07 2.12 2.00 Temperature [°C.] 83 86 80 MFR₂ [g/10 min] 37.0 38.0 45.0 C2 content [mol-%] 6.1 6.36.2 H₂/C3 ratio [mol/kmol] 49.8 56.9 60.8 C2/C3 ratio [mol/kmol] 22.722.1 25.0 amount [wt.-%] 48 53 55 Final MFR₂ [g/10 min] 35.0 40.0 45.0C2 content [mol-%] 5.3 5.2 5.3 XCS [wt.-%] 8.1 8.1 5.6 Mw [kg/mol] 152160 147 Mw/Mn [—] 4.4 4.3 4.2 2,1 [%] n.d. n.d. n.d. n.d. not detectable

All polymer powders were compounded in a co-rotating twin-screw extruderCoperion ZSK 57 at 220° C. with 0.2 wt.-% of Irganox B225 (1:1-blend ofIrganox 1010(Pentaerythrityl-tetrakis(3-(3′,5′-di-tert.butyl-4-hydroxytoluyl)-propionateand tris(2,4-di-t-butylphenyl)phosphate)phosphite) of BASF AG, Germany)and 0.1 wt.-% calcium stearate. The materials of the inventive examplesIE1 and IE2 were nucleated with 2 wt.-% of a propylene homopolymerhaving an MFR₂ of 20 g/10 min and 200 ppm of vinylcycloalkane polymer(pVCH) to give inventive examples IE3 and IE4, respectively. In the sameway, the material of comparative example CE1 was nucleated with 2 wt.-%of a propylene homopolymer having an MFR₂ of 20 g/10 min and 200 ppm ofvinylcycloalkane polymer (pVCH) to give comparative example CE2.

TABLE 3 Relative content of isolated to block ethylene sequences (I(E))Example 1E3 1E4 CE2 n-PEP¹⁾ [%] 65.4 65.3 72.1 EEE [mol-%] 0.61 0.610.42 EEP [mol-%] 0.98 1.38 1.11 PEP [mol-%] 3.01 3.75 3.95 PPP [mol-%]88.7 85.88 86.28 EPP [mol-%] 6.70 8.10 8.02 EPE [mol-%] 0.00 0.28 0.21¹⁾${I(E)} = {\frac{fPEP}{\left( {{fEEE} + {fPEE} + {fPEP}} \right)} \times 100\mspace{11mu} (I)}$

1. Propylene copolymer (R-PP) having: (a) a comonomer content in therange of 2.0 to 11.0 mol. %; (b) a melt flow rate MFR2 (230° C.)measured according to ISO 1133 in the range of 25.0 to 100 g/10 min; and(c) a relative content of isolated to block ethylene sequences (I(E)) inthe range of 45.0 to 70.0%, wherein the I(E) content is defined byequation (I): $\begin{matrix}{{I(E)} = {\begin{matrix}{fPEP} \\\left( {{fEEE} + {fPEE} + {fPEP}} \right)\end{matrix} \times 100}} & (I)\end{matrix}$ wherein: I(E) is the relative content of isolated to blockethylene sequences [in %]; fPEP is the mol fraction ofpropylene/ethylene/propylene sequences (PEP) in the sample; fPEE is themol fraction of propylene/ethylene/ethylene sequences (PEE) and ofethylene/ethylene/propylene sequences (EEP) in the sample; fEEE is themol fraction of ethylene/ethylene/ethylene sequences (EEE) in the samplewherein all sequence concentrations being based on a statistical triadanalysis of ¹³C-NMR data.
 2. Propylene copolymer (R-PP) according toclaim 1, wherein said propylene copolymer (R-PP) has a xylene coldsoluble fraction (XCS) in the range of 4.0 to 25.0 wt. %.
 3. Propylenecopolymer (R-PP) according to claim 1, wherein said propylene copolymer(R-PP) has: (a) a glass transition temperature in the range of −12 to+2° C.; and/or (b) no glass transition temperature below −20° C. 4.Propylene copolymer (R-PP) according to claim 1, wherein said propylenecopolymer (R-PP) has: (a) a main melting temperature in the range of 133to 155° C.; and/or (b) a crystallization temperature in the range of 110to 128° C.
 5. Propylene copolymer (R-PP) according to claim 1, whereinsaid propylene copolymer (R-PP) has: (a) has 2,1 regio-defects of atmost 0.4% determined by ¹³C-NMR spectroscopy; and/or (b) is monophasic.6. Propylene copolymer (R-PP) according to claim 1, wherein thecomonomer is selected from ethylene, C₄ to C₁₂ α-olefin, and mixturesthereof.
 7. Propylene copolymer (R-PP) according to claim 1, whereinsaid propylene copolymer (R-PP) comprises two fractions, a firstpropylene copolymer fraction (R-PP1) and a second propylene copolymerfraction (R-PP2), said first propylene copolymer fraction (R-PP1)differs from said second propylene copolymer fraction (R-PP2) in thecomonomer content.
 8. Propylene copolymer (R-PP) according to claim 7,wherein: (a) the weight ratio between the first propylene copolymerfraction (R-PP1) and the second propylene copolymer fraction (R-PP2)[(R-PP1):(R-PP2)] is 70:30 to 30:70; and/or (b) the comonomers for thefirst propylene copolymer fraction (R-PP1) and the second propylenecopolymer fraction (R-PP2) are selected from ethylene, C₄ to C₁₂α-olefin, and mixtures thereof are the same and are selected fromethylene, C₄ to C₁₂ α-olefin, and mixtures thereof.
 9. Propylenecopolymer (R-PP) according to claim 7, wherein: (a) the first propylenecopolymer fraction (R-PP1) is the comonomer lean fraction and the secondpropylene copolymer fraction (R-PP2) is the comonomer rich fraction,and/or (b) the first propylene copolymer fraction (R-PP1) has a lowercomonomer content than the propylene copolymer (R-PP).
 10. Propylenecopolymer (R-PP) according to claim 7, wherein: (a) the first propylenecopolymer fraction (R-PP1) has a comonomer content in the range of 1.0to 6.0 mol-% based on the first propylene copolymer fraction (R-PP1);and/or, (b) the second propylene copolymer fraction (R-PP2) has acomonomer content in the range of more than 6.0 to 14.0 mol % based onthe second propylene copolymer fraction (R-PP2).
 11. Propylene copolymer(R-PP) according to claim 7, wherein: (a) the first random propylenecopolymer fraction (R-PP1) and the second random propylene copolymerfraction (R-PP2) fulfill together the in-equation (V): $\begin{matrix}{{\frac{{Co}\left( {R - {{PP}\; 2}} \right)}{{Co}\left( {R - {{PP}\; 1}} \right)} \geq 1.0};} & ({IV})\end{matrix}$ wherein: Co(R-PP1) is the comonomer content [mol. %] ofthe first propylene copolymer fraction (R-PP1), Co(R-PP2) is thecomonomer content [mol. %] of the second propylene copolymer fraction(R-PP2)₁ and/or, (b) the first random propylene copolymer fraction(R-PP1) and the random propylene copolymer fraction (R-PP) fulfilltogether the in-equation (V): $\begin{matrix}{\frac{{Co}\left( {R - {PP}} \right)}{{Co}\left( {R - {{PP}\; 1}} \right)} \geq 1.0} & (V)\end{matrix}$ wherein: Co(R-PP1) is the comonomer content [mol. %] ofthe first propylene copolymer fraction (R-PP1), Co(R-PP) is thecomonomer content [mol. %] of the propylene copolymer (R-PP). 12.Injection molded article comprising a propylene copolymer according toclaim
 1. 13. Thin wall packaging made by injection molding, comprising apropylene copolymer according to claim
 1. 14. Process for producing apropylene copolymer (R-PP) according to claim 1, wherein the propylenecopolymer (R-PP) has been produced in the presence of: (a) aZiegler-Natta catalyst (ZN-C) comprises a titanium compound (TC), amagnesium compound (MC) and an internal donor (ID), wherein saidinternal donor (ID) is a non-phthalic acid ester, (b) optionally aco-catalyst (Co), and (c) optionally an external donor (ED).
 15. Processaccording to claim 14, wherein: (a) the internal donor (ID) is selectedfrom optionally substituted malonates, maleates, succinates, glutarates,cyclohexene-1,2-dicarboxylates, benzoates and derivatives and/ormixtures thereof; (b) the molar-ratio of co-catalyst (Co) to externaldonor (ED) [Co/ED] is 5 to
 45. 16. Process according to claim 14,wherein the propylene copolymer (R-PP) is produced in a sequentialpolymerization process comprising at least two reactors (R1) and (R2),in the first reactor (R1) the first propylene copolymer fraction (R-PP1)is produced and subsequently transferred into the second reactor (R2),in the second reactor (R2) the second propylene copolymer fraction(R-PP2) is produced in the presence of the first propylene copolymerfraction (R-PP1).